Tool Aims to Reduce Biopsies

Photonics.comMar 2009
BOZEMAN, Mont., March 30, 2009 -- A handheld microscope that uses laser light to form an image of the skin's cellular structure could someday reduce the number of biopsies needed to diagnose skin cancer.

Biopsies -- invasive, often painful procedures to remove skin samples for analysis -- are currently the best way to diagnose melanoma and other skin cancers. Millions are conducted each year in the US, and according to the American Cancer Society, most of them -- as many as 80 percent for some types of cancers -- come back negative.

Montana State University (MSU) electrical engineering department researcher Chris Arrasmith worked with doctors at Vanderbilt Medical Center in Tennessee to build the handheld laser microscope, which could help doctors get a better idea of when biopsies are absolutely necessary.

That would cut down on the number of biopsies that have to be performed and streamline the process of diagnosing cancers, Arrasmith said. Montana State University researcher Chris Arrasmith with the handheld laser microscope he built in collaboration with doctors at Vanderbilt University. (MSU photos by Kelly Gorham)
"Any combination of tools we can provide to enable early detection of any kind of disease is a good thing," said Arrasmith.

Like most microscopes, the MSU-Vanderbilt device uses lenses to look at a patient's skin, but instead of illuminating the skin with normal white light, the device uses laser light.

The laser light is used to form an image of the skin's cellular structure, and it monitors the way a patient's cells change the reflected laser light, Arrasmith said. Those changes to the light can tell scientists the chemical composition of the skin cells -- a process called spectroscopy.

"Within the microscope's image, we can select an area of interest, and from that we can take a spectrum and get chemical data," he said.

Doctors would then compare that chemical signature to a database containing the chemical signatures of known cancers to see whether the patient's cells are cancerous.

The project, which Arrasmith began working on when he was an undergraduate, is funded by a five-year, $1.79 million grant from the National Institute of Biomedical Imaging and Bioengineering (NIBIB), part of the National Institutes of Health. The NIBIB focuses on researching new biomedical imaging devices and techniques to improve the detection, treatment and prevention of disease.

David Dickensheets, an associate professor of electrical and computer engineering at MSU and adviser to Arrasmith's work, said other labs have built microscopes that work on the same principles, but they have been desktop instruments that still required skin samples to be taken from patients. A closeup of the laser microscope built by MSU and Vanderbilt University, with its inner workings exposed.
Shrinking the device combines microscopy with microelectricalmechanical systems, or MEMS, and could produce a device that could one day find its way into dermatology clinics around the world, Dickensheets said.

The handheld microscope contains a tiny mirror made of silicon that scans the laser beam across the skin, Dickensheets said. This allows the microscope to form an image and lets it look at cells beneath the patient's outer skin layer.

"We think that microscopic imaging of cell structure combined with the chemical specificity provided by spectroscopy is the real key to making it a useful tool," Dickensheets said.

Arrasmith built a prototype microscope that's now being tested at Vanderbilt's medical clinics. He recently earned his master's degree at MSU and will soon leave the university. He hopes the second-generation model of the microscope, which he won't be around to see, will be about the size of a chalkboard eraser.

"As a person who likes to see things from start to completion, it's difficult to leave in the middle of a long project like this," he said.

But he said the experience he's gained from having a hand in every aspect of the project -- from theory and design to machining parts -- will give him a leg up in searching for an engineering job after he leaves MSU.

An instrument consisting essentially of a tube 160 mm long, with an objective lens at the distant end and an eyepiece at the near end. The objective forms a real aerial image of the object in the focal plane of the eyepiece where it is observed by the eye. The overall magnifying power is equal to the linear magnification of the objective multiplied by the magnifying power of the eyepiece. The eyepiece can be replaced by a film to photograph the primary image, or a positive or negative relay...

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